Pneumatic tool



(No Model.)

0. B. ALBREE. PNEUMATIC TOOL.

Patented Dec. 1, 1896.

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UNITED STATES PATENT OFFICE.

CHESTER B. ALBREE, OF ALLEGHENY, PENNSYLVANIA.

PNEUMATIC TOOL.

SPECIFICATION forming part of Letters Patent No. 572,324, dated December1, 1896.

Application filed May 15, 1896.

To all whom it may concern:

Be it known that I, CHESTER B. ALBREE, of Allegheny, in the county ofAllegheny and State of Pennsylvania, have invented a new and usefulImprovement in Pneumatic Tools, of which the following is a full, clear,and exact description, reference being had to the accompanying drawings,forming part of this specification, in which- Figure 1 is a longitudinalsection of my improved mechanism. Fig.2 is a cross-section on line 2 2,and Figs. 3 and 4 are longitudinal sections of modified forms.

My invention relates to that class of pneumatic or steam reciprocatingmotors or tools known as the valveless tools, in which the piston itselfoperates as the controlling-valve to govern the admission and exhaust ofpressure, and it is designed to afford an increase in the efficiency ofthe motor or tool without a corresponding increase in the pneumatic orsteam pressure required. The mechanism hereinafter described thatis usedfor contain ing and actuating the piston is of a type well known and ingeneral use, and the specific form shown in the accompanying drawingsmay be varied without departure from my invention.

In the drawings, A indicates the body of the machine, having a cylinderBB, provided with a removable head a.

O O is the piston, the two parts of which are of unequal diameters.

D is an inlet-valve controlling the admission of steam or air underpressure through supply-pipe b to inlet-port c. It is provided withsuitable means for opening and closing, (herein represented by a rod (2and closingspring 6.) V

f g h are ports in cylinder B, connected by a by-pass E, and z is theexhaust-port, so placed in relation to the piston O that it is uncoveredthereby only at the end of the outward or working stroke.

F is a passage or recess in piston (l of a length sufficient to uncoverand connect with port fwhen the piston is at the end of its outward orworking stroke.

7' is an annular shoulder at the end of the piston 0, upon which thepressure is exerted in its inward stroke. The piston C has avalve-chamber H H communicating through Serial No. 591,638. (No model.)

a, port G with the exterior of the piston at the shoulder r, and havingtherein a valve L, preferably of the puppet type, adapted to close thepassage between the parts H and H of the chamber in the piston andnormally retained in an open position by the pressure of a spring Z.

m is an air-vent in the-outer portion of the chamber 13, which servestoprevent the formation of an air-cushion.

it indicates the shank of the tool inserted in its proper position.

0 is a pin projecting inwardly from the cylinder B, adjustable by meansof its threaded portion, which fits in a corresponding slot 19 in piston0 (indicated in Fig. 1 by broken lines) and serves as a guide topreserve the relation of passage F to the ports f g h, as indicated.

In Fig. 3 I show a modification in which the chamber F of Fig. 1 is anannular recess in the circumference of the piston 0, whereby thenecessity of the guiding-pin and slot is avoided, and in Fig. 4; I showyet another modification in which port 9 is omitted, and passage F ofFig. 1 connects directly with cylinder B by means of an opening throughthe face of piston O.

The operation is as follows: Steam or air under pressure is admittedthrough the inletpipe I), by means of valve D, to port 0 and exerting apressure on shoulder r of the piston 0 causes it to recede from theposition as shown in Figs. 1, 3, and 4.. At the same time pressure isexerted upon valve L through passage G and chamber H, overcoming thepressure of spring Z, and the pressure in chambers B E and passage Fbeing practically neutral causes said valve L to close,thus preventingany communication between port 0 and passage F and through port f withchamber B. When the shoulder rof the piston has passed port f, pressureis instantly exerted therethrough to thepassage E and through port It tothe cylinder B and upon the entire surface of the face of the piston 0,thus causing a reversal of its motion. By reason of port 9 pressure isexerted through chamber H and passage F upon valve L, and being equaland balanced upon both sides of said valve allows it to be moved into anopen position by the spring Z, thus permitting com munication betweeninlet-port c and passage F after the shoulder 7 has passed port f on theoutward or working stroke of the piston. There is communication,therefore, between inlet-port c and cylinder B in the rear of the pistonthroughout the entire outward or working stroke. As the piston reachesthe end of this stroke it uncovers the exhaustport 2, and by reducingthe pressure in the cylinder B causes a corresponding reduction ofpressure on the valve L, thereby causing said valve to close by reasonof the constant pressure through the passage G. The piston and the valveL are then in their original positions and the operation as abovedescribed is repeated.

In Fig. 3 I show a modification of the device in which the valve L isset in a position lengthwise of the piston instead of being transverse,as in Fig. 1, and in which the passage F extends entirely around thepiston. In Fig. 4 I show a modification wherein the necessity of usingthe port 9 is obviated by causing passage F to connect directly withcylinder B. Many other changes may be made without departure from myinvention as defined in the claims.-

The advantages of my improvement will be appreciated by those skilled inthe art to which it relates. Its parts are few in number, simple inconstruction, durable, and in operation entirely automatic.

Hitherto in the operation of motors of the class to which my inventionrelates there has been and must of necessity be a loss of power in theoutward or working stroke. The pressure upon the shoulder r or forwardend of the piston necessary to produce the return motion of the pistonis constant, and while in the ordinary style of tool when the saidshoulder of the piston has passed the port f in its inward stroke thefull pressure is admitted through port f to the cylinder B and permitsthe exertion of the full pressure upon the larger surface of the piston,it is almost instantly cut off through the closing of the port f on theoutward stroke of the piston, and the force of said stroke thereafterdepends upon that proportion of the pressure due to the expansion of thesteam or air in the cylinder B in excess of the'constant'pressure on theother end of the piston that tends to retard the stroke.

By the use of my invention this loss in the outward or working stroke isentirely removed, since the pressure upon each side of valve L is equal,after the opening of port f, to the pressure by the passage of shoulderr in the inward stroke of the piston and remains open during the outwardstroke by reason of this equality of pressure thereon remainingconstant. There is therefore a free passage for the steam or air fromthe inlet 0 to the cylinder B back of the piston during the entireoutward or working stroke, or until the opening of the exhaust-port 'i.

The apparatus may be used for actuating rock-drills, for hand chippingor calking tools, and for any'other purpose where a rapid reciprocatingmotion is desired.

I claim 1. A reciprocating tool having a cylinder and piston, anexhaust-port, a port adapted to be uncovered at the end of the instrokeof the piston to admit fluid-pressure to the rear of the piston and tocause its initial outstroke, a passage through the piston to admitfluidpressure to the rear of the piston after the beginning of theoutstroke, and a valve which controls said port and is closedautomatically when the pressure at the rear of the piston is reduced byexhaustion.

2. A reciprocating tool having a cylinder and piston, an exhaust-port, aport adapted to be uncovered during the instroke of the piston to admitfluid-pressure to the rear of the piston and to cause its initialoutstroke, a passage through the piston to admit fluidpressure to therear of the piston thereafter, and a valve which controls said port andis closed automatically when the pressure at the rear of the piston isreduced by exhaustion, said valve being subjected on one side to theclosing pressurefrom the cylinder at the outer end of the piston and onthe other side to the pressure from the inner end thereof.

3. A reciprocating tool having a cylinder and piston, an exhaust-port, aport adapted to be uncovered during the instroke of the piston to admitfluid-pressure to the rear of the piston and to cause its initialoutstroke, a chamber II, II in the piston, a passage F adapted toregister with a port leading to the rear portion of the cylinder, acheck-valve in said passage, and a valve-controlled port admitting fluidto the forward portion of the cylinder.

4. A reciprocating tool having a cylinder.

and piston, the effective area of the piston exposed to pressure beinggreater at the rear end than at the forward end, and a pressureinletport, admitting constant fluid-pressure to the smaller end of thepiston, an exhaustport, a port adapted to be uncovered during theinstroke of the piston to admit fluid-pressure to the rear of the pistonand to cause its initialbutstroke, a passage through the piston to admitfluid-pressure to the rear of the piston thereafter, and a valve whichcontrols said port and is closed automatically when the pressure at therear of the piston is reduced by exhaustion.

In testimony whereof I have hereunto set my hand.

CHESTER I). ALBREE. Vitnesses:

THOMAS W. BAKEWELL, G. I. HoLDsHIP.

ICC

